Dispersion of Light

[hhhmortal]

Hello, I have this question which I'm having trouble in answering myself:<br /><br /><br />How at some regions of the electromagnetic spectrum, spectral information can be gained without dispersion?<br /><br />Also, what would happen to the operation of a charge coupled device at wavelengths other than optical?.<br /><br />Is that at bigger wavelengths less charge released, and at smaller wavelengths more charge released?<br /><br />Thanks a lot

 

[jgreimer]

Although Einstein didn't discover the photoelectric effect he was the first to explain it. In doing so he greatly contributed to the quantum theory, which he later rejected, and won the Nobel prize.<br /><br />What he discovered was that at wavelengths below a maximum, the number of electrons (charge) released is dependent only upon the intensity of the light, not on the wavelength. The shorter the wavelength however, the more energy the electrons have. Light at wavelengths longer than the maximum wavelength, do not cause any electrons to be released.<br /><br />http://en.wikipedia.org/wiki/Photoelectric_effect

 

[billslugg]

I do not know what you mean by "no dispersion". All transmissive media have indexes of refraction that vary as a function of EM wave frequency as far as I know. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[sssalvi]

How at some regions of the electromagnetic spectrum, spectral information can be gained without dispersion?<br /><br />Dispersion exists for all regions. ... Is there any specific instance that you have in mind?<br /><br />Also, what would happen to the operation of a charge coupled device at wavelengths other than optical?.<br /><br />All CCDs manufacturers will provide a sensitivity table of Incident Wavelength vs Output.<br /><br />

 

[hhhmortal]

Well its just that, there's this question which says:<br /><br />Discuss the various methods of dispersing radiation to produce a spectrum. Explain how at some regions of the electromagnetic spectrum information can be gained without dispersion.<br /><br />I suppose what they mean about dispersion is when electromagnetic waves are diffracted perhaps.?

 

[billslugg]

I am sorry, but we generally do not do homework for people. Is that what this is? <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[hhhmortal]

No its not homework, its questions which im getting from a magazine i bought, and im rather intrigued...

 

[billslugg]

OK.<br /><font color="yellow">Explain how at some regions of the electromagnetic spectrum information can be gained without dispersion. </font><br /><br />The statement does not make sense. There is no portion of the EM spectrum that is immune from the effects of dispersion. The EM is just there. The dispersion is a property of the medium through which the EM waves are traveling. <br /> <br />The only medium for which there is no dispersion is a perfect vacuum. And that applies to all regions of the EM spectrum equally.<br /><br />Could you give a bit more detail on the magazine article? I am trying to understand where they are coming from. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[hhhmortal]

I totally agree with you. It talks about the diffraction of light using prisms and diffraction gratings.